Method and apparatus for applying rivets



April 17, 1962 c. w. BAUGH ETAL 3,029,565

METHOD AND APPARATUS FOR APPLYING RIVETS Filed Sept. 5, 1957 3 Sheets-Sheet 1 0% v/ fier d ij fl M12? 7172.

INVENTO 34 flrr u /s.

C W. BAUGH ETAL METHOD AND APPARATUS FOR APPLYING RIVETS Filed Sept. 3, 1957 April 17, 1962 4A m umw. n M E m? & w ay m W2 ,0 m MM S I 3 2 z April 1962 c. w. BAUGH ETAL 3,029,665

METHOD AND APPARATUS FOR APPLYING RIVETS Filed Sept. 3, 1957 3 Sheets-Sheet 3 A "I M0 Af A 4 ALA " n ts This invention relates generally to rivets and more particularly to a method and apparatus for applying rivets.

Rivets of 'one type commonly include a stump or pin having a head and a shank provided with locking grooves. A collar which is first loosely fitted on the shank is adapted to be forced into frictionl engagement with the shank at the locking grooves by a varietyof riveting tools. Many of these tools employ an anvil of sleeve which moves longitudinally over the collar to swage the collar into the locking grooves and depend for a desired operation on a particular collar shapei Furthermore, it is well known that the fatigue life of substantially any connector is increased when a tension pre-load is maintained in the connector, that is, when the pin-is under a tension load when it has been set.

An object of this invention, therefore, is to provide an improved method and apparatus for applyingor setting rivets of the above type. i

A further object of this invention is to provide a method and apparatus for applying rivets of the above type by crimping the collar into the locking grooves in a manner such that a tension pre-load is maintained in the pin or stump.

' Another object of this invention is to provide apparatus 'for applying rivets of the above type which is adapted for attachment with rivet guns whichlare now available and 'which'is us'eable with rivet 'collars'of diiferent shapes.

A further object of this invention is to provideapparatus for applying rivetsof .the above type which is simple in construction, economical to manufacture, and efficient in operation in'setting rivets in the desired manner.

Further objects, features and advantages of the above invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

PEG. 1 is a fragmentary longitudinal sectional view of one type of a riveting gun, showing the apparatus of this invention in assembly relation therewith;

FIG. 2 is an enlarged fragmentary sectional view of a portion of the structure shown in FIG. 1, and showing the crimping jaws for the apparatus of this invention in an extended spread position;

FIG. 3 is anenlarged longitudinal sectional view, illus- I trated similarly to FIG. 2, and showing the jaws in a retracted position;

FIG; 4 is a sectional view showing a stump and collar rivet in condition for setting to connect a pair of parts;

FIGS. 5, 6 and 7 are views like FIG. 4'of the rivet shown therein, showing the successive positions of the rivet as the apparatus of this invention is applied thereto;

FIG. 8 is a view looking substantially along'the line 88 in FIG. 3; I 7

FIGS. 9, 10 and 11 are sectional views corresponding substantially to FIGS. 5, 6 and 7 showing a modified form of the apparatus of this invention in assembly relation with a rivet of the pin and collar type and another type of riveting gun; and

3,29,665 Patented Apr. 7, ssz;

in FIG. 1 in assembly relation with a riveting gun 12 of well known type. As best appears in FIG. 1, the gun 12 includes a housing 14 and a piston 16 mounted for reciprocating movement within the housing 14 and having a threaded front end portion 18. The piston 16 is formed on opposite sides with recesses 20, only one of which is shown, for receiving corresponding portions of one end of a fork member 22 supported intermediate its ends on a pivot 24 carried on a handle 26 for the gun 12. The opposite end of the fork 22 carries a roller 30 which is adapted to roll between inclined guides 32 and 34 that are movable within the handle 26 toward and away from the pivot 24. It is apparent that on movement of the guides 32 and 34 away from the pivot 24, the fork 22 is swung in a counterclockwise direction about the pivot 24 for moving the plunger 16 in a forward direction. Like- .wise, when the guides 32 and 34 are moved toward the pivot 24, the fork 22 is moved in a clockwise direction to move the piston 16 rearwardly. A trigger 28 on the handle 26 operates a hydraulic or other mechanism, in a well'known manner, to move the guides 32 and 34 in the desired direction." V

The crimping mechanism 10 includes a hollow barrel 36 having a tubular inner end portion 38 provided with diametrically opposite ears 40. The barrel 36' also includes a tubular outer end portion 42 having an inner bore section 44 and an outer bore section 46 which is of a ,slightlylarger diameter than the section 44. An intermediate section 48 of the barrel 36 has a bore 50 extended therethrough which is of a reduced size relative to both the bores 44 and 46.

Positioned within the outer end portion 42 of the barrel 36 is a tubular crimping collet 52 (FIGS. 2 and 3) having an internally threaded inner end portion 54 slid- ;ably supported within the bore section 44 The collet 52 is provided with four slots 56 located outwardly of the inner end portion 54 and terminating at their inner ends 'in holes 58. The slots 56 are equally spaced and thus Inwardly of the outer end 62 of the collet 52, each jaw 60 has atransverselyi extended relief groove 66 on its inner side and between the groove 66 and the outer end 62 each jaw is provided with a rounded radially inwardly extended projection or knob 68. An expander plug (not shown) is inserted in the collet 52 prior to heat treating of the collet so that in its final form, the collet is stressed such that the jaws60 are spread apart. as illustrated in FIGS. 1 and 2; To contract the collet 52 or, in other words, move the jaws 60 inwardly toward each other, it is necessary to move the inner end portion 54 of the collet 5 2 rearwardly in the inner bore section 44'to progressively engage the inclined jaw surfaces 64 with the outer end '70 of the barrel 36, which has a beveled inner surface portion 72 to reduce wear on the jaws 60. i

A plunger 74 slidably supported in the inner barrel portion 38 has an elongated stem 76 extended through the reduced'bore 5t) and threaded into the inner end portion 54 of the collet 52. To move the jaws 60 to fully movedapart positions, as shown in FIGS. 1 and 2, the plunger 74 is moved to a stop position engaged with the intermediate barrel portion 48. The extent of movement of the jaws 60 in directions to expand the collet 52 is of course adjustable by advancing or retracting the stem 76 withinthe collet 52 since such adjustment determines the extent of outward movement permitted the jaws 60 by the barrel 36. The contracted position of the collet 52,

3 corresponding to positions of the jaws 60 in which the jaws are moved inwardly toward each other, is illustrated in FIG. 3 and is defined by the engagement of the inner end portion 54 of the collet 52 with the intermediate barrel portion 48.

In the assembly of the crimping mechanism with the gun 12, the barrel 36 is supported on the gun casing 14 in a position in which one of the ears 40 is interlocked with the casing 14 and the end portion 18 of the piston 16 is threaded into an inner end portion 78 of the plunger 74 as shown in FIG. 1. Thus, on operation of the gun 12 to retract the piston 16, the jaws 60 are moved inwardly toward each other to the stop position of the collet 52 illustrated in FIG. 3. Conversely, on operation of the gun 12 to move the piston 16 outwardly, the jaws 60 are moved apart to the positions illustrated in FIGS. 1 and 2 corresponding to an expanded condition of the collet 52.

-In the operation of the crimping mechanism to set the rivet indicated generally at 80 in FIG. 4, assume that a pair of parts or plates 82 and 84 are to be connected by the rivet 80. The rivet 80 consists of a stump 86, extended through aligned openings 88 in the plates 82 and 84 and a collar 100 positioned on the stump 86. The

- stump 86 has a shank 92, which is illustrated as being of a size providing for an interference fit in the openings 88 although it is to be understood that such an interference fit is not required and the mechanism 10 is used with rivets in which a more loose fit is involved. In addition, the stump 86 includes a head 90 located at one end of the shank 92 and positioned in engagement with the plate 82. Adjacent its terminal end 94, the shank 92 is formed with locking grooves 96 and ridges 98 for a purpose to appear later. The collar @100 is supported on the shank 92in a position extended about the shank 92 at the grooves 96 and against the plate 84.

The gun 12 is first moved to a position in which the collet 52 is positioned about the collar 100 with the outer end 62 of the collet 52 against the plate 84 as shown in FIG. 5. A coil spring 101 positioned within the collet 52 and secured at the inner end thereof to the inner end portion 54 of the collet, has its outer end engaged with the end of the collar .100. As a result, the spring 101 acts to exert a yieldable force on the collar 100 holding the collar against the adjacent plate 8 4. The trigger 28 is then operated to retract the piston 16 to in turn retract the collet 52 relative to the barrel 36. Concurrently with this manipulation of the trigger 28, forward pressure is exerted on the gun 12 to maintain the end 62 of the collet 52 against the plate 84. As a result of this concurrent manipulation of the gun 12 and the trigger 28, the barrel 36 is in efiect moved toward the plate 84 to move the jaws 60 inwardly toward each other as illustrated in FIG. 6.

The curved projections 68 on the jaws 60 thus act to squeeze or crimpthe collar 100 as shown in FIG. 6 so that the collar is progressively swaged into engagement with the locking grooves 96. By virtue of this swaging, the collar 100 is interlocked with the shank 92 at'the grooves 96 and the ridges 98. Continued movement of the barrel 36 toward the plate 84, therefore, acts to further pinch or squeeze the collar 100 so that the collar material is moved in a direction axially of the collar.

Since the collar is engaged with both the plate 84 and the ridges 98, the shank 92 is effectively pulled over the length thereof between the head 90 and the ridges 98. As a result, the plates 82 and 84-are pulled tightly together to insure a complete pull through of the stump 86 and eliminate any gap between, the plates, as shown in FIGS. 6 and 7. In the final set position of the rivet 80, the collar 100 has been effectively lengthened as illustrated in FIG. 7 to in turn stretch the shank 92 and apply a tensile pre-load to the stump 86. In other words,

by virtue of the curved projections 68 on the jaws 60, g

the collar material is first interlocked with the stump 92 at the ridges 98 and the grooves 96 following which the collar material is further expanded or stretched in an axial direction to apply a tensile pre-load to the stump. Such a pro-load effectively increases the fatigue life of the rivet 80, and prevents any loosening of the stump or the collar during use of the parts 82 and 8 4.

Two locking grooves 96 and ridges 98 are illustrated for the rivet 80 so that the rivet can be used for connecting workpieces 82 and 84 of thicknesses within predetermined limits or grip lengths.

A modified form of the crimping mechanism of this invention, indicated generally at 10a, is illustrated in FIGS. 9-l3, inclusive. The mechanism 10a is adapted for assembly with ariveting mechanism of 'well known type, indicated generally at 120, which includes an outer sleeve or anvil member 122 having an inwardly tapered inner surface =124adjacent its terminal end 126. The mechanism also includes a plurality of jaws 128 which are adapted to be contracted and moved rearwardly within the sleeve 122 by a jaw contracting and moving element 130.

A pull member (not shown) like the plunger 74 for the pull gun 12 illustrated in FIG. 1 is associated with the element 130 for selectively moving the element 130 rearwardly within the sleeve 122.

The crimping mechanism'10a includes a collet. 132 having a tubular inner end portion 134 positioned within the sleeve 122. The collet 132 is provided with four equally spaced slots 136 extending outwardly from the inner end portion 134 to divide the collet into four jaws .or fingers 140 arranged in a circular formation'transversely of the collet 132. Over the length of the jaws 140, the collet 132 is of a uniformly increasing diameter to pro vide each jaw with an outwardly inclined outer surface 142 for a purpose to appear late'r. Inwardly of the outer end 1440f the collet 132, each jaw 140 is formed with a transversely extended relief groove 146 bounded on its inner side by an inwardly inclined surface 148. A

The collet 132 is initially heat treated like the collet 52 previously described so that the collet is stressed to p o vide for a natural outward flaring of the jaws 140. To reduce the substantially circular area bounded by the jaws 140, they must be manually moved inwardly toward each other. In the illustrated embodimentof the invention shown in FIGS. 9-13, this is accomplished by moving the sleeve 122 toward a position completely surrounding I an expanded condition of the collet 132, is illustrated in FIG. 9. The inwardly moved position of the jaws 140, corresponding to a contracted condition of the collet 132, is illustrated in FIG. 11. The natural tendency of the jaws 140 to move away from each other and the cooperating sliding surfaces 124 and 142 provide for an automatic movement of the collet 132 from the FIG. 11 to the FIG. 9 position whenever the reaction force on the sleeve 122 is released. A set screw 150 carried by the inner end portion 134 of the collet 132 is guidably supported in a slot 152 in the sleeve 122 to prevent accidental movement of the collet 132 out of an assembly relation with the sleeve 122. V

In the operation, of the crimping mechanism 10a to set the rivet indicated generally at 154 in FIGS. 10 and 11, and connect a pair of plates 156 and 158, the mechanism 10a is initially moved to the position illustrated in FIG. 9. As shown in FIG. 9, the rivet 154 includes an elongated pin 160 formed with a head 161 and a shank 163 extended through the plates 156 and 158. The shank 163 is formed with locking grooves 162 like the locking grooves 96 formed on the stump 86 and, in addition, is provided with a tail or pull portion 164 formed with pull grooves 166 adapted to be engaged by the jaws 128 on the riveting mechanism 120. Between the locking grooves 162 and the pull grooves 166, the shank 163 has the usual breakneck groove 168. The rivet 154 also includes a tubular collar 1'70 supported on the shank 163 at a position extending about the pull grooves 162 and with one end against the plate 158.

With the mechanism a in the position illustrated in FIG. 9, the jaws 140 encircle the collar 170 and the inclined jaw surfaces 148 are in engagement with the outer end 172 of the collar 170 for maintaining a pressure against the collar 170 to continuously hold the collar in a position against the adjacent plate 158. The gripping jaws 128 are in engagement with the pin 160 at the pull grooves 166 and when the riveting mechanism 120 is operated to retract the jaws 128 a pull is exerted on the pin 160. The reaction force to this pull is applied in an opposite direction through the sleeve 122 to the jaws 140. Accordingly, the sleeve 122 is moved toward the plate 158 with the sleeve surface 124 sliding on the jaw surfaces 142 to progressively move the jaws 140 inwardly toward each other as illustrated in FIG. 10. 7

Each jaw is formed with a curved knob or inward projection 176 which acts in response to inward movement of the jaws 140 to squeeze or crimp the collar 170* as shown in FIG. 10 so that the collar, intermediate its ends, is progressively swaged into engagement with the shank 163 at the locking grooves 162. By virtue of this swaging, the collar 170 is interlocked with the pin 160 at the grooves 162.

shank 163, acts to further pinch or squeeze the collar 170 so that the collar material is extended in a direction axially of the collar. As best appears in FIGS. 9, 10 and 11, the jaws 140 are of a length outwardly of the inclined surfaces 148 and relative to the length of the collar 170 such that clearance is provided between the outer ends 144 of the jaws 140 and the plate 158 during crimping of the collar 170. On crimping movement of the jaws 140, the inclined jaw surfaces 148 ride on the outer end of the collar 170 so as to continually exert the desired force on the collar 176 for maintaining the collar in position against the plate 158.

The pulling force on the pin 160 provides the desired pull together of the plates 156 and 158 prior to any swaging of the collar 170. After initial swaging of thecollar 170 into the groovesv 162, continued crimping of the collar provides for an elongating of the collar between the grooves 162 and the plate 158. Since the collar is engaged with both the plate 158 and the pin 160 at the grooves 162, this elongating of the collar causes a pulling force to be exerted on the pin between the pin head and the grooves 162. In other words, the collar 170 is lengthened to in turn stretch the pin 160 and apply a tensile pre-load to the pin. Continued pull on the jaws 128 causes the usual fracture of the shank 163 at the breakneck groove 168. This sequence of operation is insured merely by forming the collar 170 of a material which is of a requisite hardness, without requiring special collar shapes to develop hold 01f as is the case with most riveting apparatus now in common use. if the collar material is too soft, the collar may be swaged into the locking grooves on the shank before the plates to be connected to several embodiments thereof, it is to be understood a have been pulled tightly together or before the pin has been completely pulled through the plate openings. In the event the collar is too hard, the pin 160 may fracture prematurely beforethe desired swaging has been accomplished.

'From the above description, it is seen that this invention provides crimping mechanisms 10 and 16a for applying a collar to the shank of a stump or a pin for a rivet. It is apparent that the mechanisms 10 and Ma are not limited to use with a collar of any particular shape. Accordingly, specially shaped collars are not required when setting rivets with the mechanisms 10 and 16a. Furthermore, as a result of the fact that the mechanisms of this invention are not limited to use with any particular collar shape, they are readily used to salvage improperly swaged collars which have been applied with rivet setting mechanisms of conventional type.

It is to be understood that while the crimping mechanism 10 has been particularly described with respect to its use with the gun 12, it is useful with any tool which is operable to apply a pull to the plunger 74 to contract the jaws 60. Also, the mechanism 10a is usable with any rivet setting device which will concurrently apply-a pull to the pin 1611 and contract the jaws 140.

Although the invention has been described with respect that it is not to be so limited, since changes can be made therein which are within the scope of this invention as defined by the appended claims.

What is claimed is: a

1. Apparatus for applying a fastener which includes a pin having a head and a shank and locking grooves formed in the shank at a position spaced from said head and a collar disposed on said shank at a position in radial alignment with said locking grooves, said apparatus comprising a tool having a tubular barrel provided with an open end, a tubular collet provided with a plurality of slots extending lengthwise thereof from one end of the collet and terminating short of the opposite end thereof to form a plurality of elongated jaws, said jaws being spaced apart circumferentially of said collet and arranged in a spread-apart formation about the axis of said collet so that at said one end thereof said collet is of a diameter greater than the inner diameter of said open barrel end, said collet being supported in said barrel so that said one end thereof projects out of said open barrel end, said collet and barrel being movable relative to each other in an axial direction to provide for movement of the collet inwardly of the open end of the barrel so that the barrel moves said jaws radially inwardly of the collet at said one end of the collet, said collet having an annular stop therein concentric with the axis thereof and surrounding an axial opening through which said pin can extend so that said stop is positionable about said pin in engagement with one end of said collar.

2. Apparatus for applying a fastener which includes a pin having a head and a shank and locking grooves formed in the shank at a position spaced from said head and a collar disposed on said shank at a position in radial alignment with said locking grooves, said apparatus comprising a tool having a tubular barrel provided with an open end, a tubular collet provided with a plurality of slots extending lengthwise thereof from one end of the collet and terminating short of the opposite end thereof to form a plurality of elongated jaws, said jaws being spaced apart circumferentially of said collet and arranged in a spread-apart formation about the axis ofrsaid collet so that at said one end thereof said collet is of a diameter greater than the inner diameter of said open barrel end, said collet being supported in said barrel so that said one end thereof projects out of'said open barrel end, means on said tool connected to the opposite end of said collet for effecting a relative movement of the collet and barrel to provide for movement of the collet in a direction inwardly of the barrel so that the barrel moves said jaws radially inwardly of the collet at said one end of the collet, said collet having an annular stop therein concentric with the axis thereof and surrounding an axial opening through which said pin can extend so that said stop is positionable about said pin in engagement with one end of said collar.

3. Apparatus for applying a fastener which includes a pin having a head and a shank and locking grooves formed in the shank at a position spaced from said head and a collar disposed on said shank at a position in radial alignment with said locking grooves, said apparatus comprising a tool having a tubular barrel provided with an open end, a tubular collet provided with a plurality of slots extending lengthwise thereof from one end of the collet and terminating short of the opposite end thereof to form a plurality of elongated jaws, said jaws being spaced apart ciroumferentially of said collet and arranged in a spread-apart formation about the axis of said collet so that at said one end thereof said collet is of a diameter greater than the inner diameter of said open barrel end, said collet being supported in said barrel so that said one end thereof projects out of said open barrel end, means on said tool connected to the opposite end of said collet for effecting a relative movement of the collet and barrel to provide for movement of the collet in a direction inwardly of the barrel so that the barrel moves said jaws radially inwardly of the collet at said one end of the collet, said collet having an annular stop therein concentric with the axis thereof and surrounding an axial opening through which said pin can extend so that said stop is positionable about said pin in engagement with one end of said collar, and radially inwardly extending rounded projections on said jaw members at said one end of the collet.

4. Apparatus for applying a fastener which includes a pin having a head and a shank and locking grooves formed in the shank at a position spaced from said head and a collar disposed on said shank at a position in radial alignment with said locking grooves, said apparatus comprising a tool having a tubular barrel provided with an open end, a tubular collet provided with a plurality of slots extending lengthwise thereof from one end of the collet and terminating short of the opposite end thereof to form a plurality of elongated jaws, said jaws being spaced apart circumferentially of said collet and arranged in a spread-apart formation about the axis of said collet so that at said one end thereof said collet is of diameter greater than the inner diameter of said open barrel end, said collet being supported in said barrel so that said one end thereof projects out of said open barrel end, means on said tool connected to the opposite end of said collet for effecting a relative movement of the collet and barrel to provide for movement of the collet in a direction inwardly of the barrel so that the barrel moves said jaws radially inwardly of the collet at said one end of the collet, said collet having an unobstructed space at the axis thereof extending substantially the full length of said jaws for receiving said shank when said one end of the collet is positioned so that it surrounds a collar on said shank, radially inwardly extending rounded projections on said jaw members at said one end of the collet, and a spring member positioned concentrically within and secured to said collet so that one end of said spring member is adjacent said projections, said spring member being positioned so that it surrounds said unobstructed space and is resiliently engageable at said oneiend thereof with said collar.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,593 Goodwin Oct. 28, 1930 2,114,493 Huck Apr. 19, 1938 2,375,574 Metheny May 8, 1945 2,396,001 Fischer Mar. 5, 1946 2,527,307 Huck Oct. 24, 1950 2,542,376 Torresen Feb. 20, 1951 2,670,118 Young Feb. 23, 1954 2,764,045 Koenig Sept. 25, 1956 2,836,888 Hargrove June 3, 1958 

